The Beginning of the End

Boss: Raum-Kampfjet Mark V (RK5) This boss battle is challenging due to the RK5 itself and the constant presence of Guardian and Lost Legion enemies. Focus on the boss unless minions are overwhelming or you need a Second Wind. The RK5 flies erratically, making it hard to hit. Its attacks include homing electric balls, missiles, and a ground slam. Its most devastating attack is a bombing run, telegraphed by the boss speaking and ground markers.

Use cover (press the cover button to crouch behind walls or objects) (press the cover button to crouch behind walls or objects) extensively, as being in the open is dangerous. Good cover spots include the entryway and the middle tower (accessible via a jump pad). Another option is the base of the middle building near a Guardian spawn. The RK5 does not have a regenerating shield. Corrosive weapons are generally more effective than others, while cryo is not very effective. The cockpit is a weak point if you get a clear shot.

After grounding the RK5, enter the large building and proceed to Tycho's Ribs. This area is a tower with elevators that rise and kill you by hitting a barrier, except for one that leads to a secret easter egg.

You cannot simply jump down to lower levels without dying. Enemies include Lost Legion (including Eternals) and Guardians.

Head down via the ramp and drop down the hole with the elevator platform. Continue descending until you reach the second side room, the Particle Collection Chamber. Circle around to the other side to continue down.

On the next level, Jack will mention a shield. Avoid the rocks in this area as they are hazardous.

Proceed past the elevator into a long hallway with more enemies. You will reach a shield and a large cannon. You can either stand in front of the shield to bait Lost Legion enemies into shooting it (earning a Challenge) or kill the cannoneer and operate the cannon yourself.

Navigate the final hallway to reach the exit to Eleseer, the last area of the game.

Eleseer: This final story area is small and populated by Guardians, including the Opha. Ophas are dangerous as they spit out Puttis, which can either restore Opha shields or create turrets.

Proceed down the only available path to an Opha enemy. If you kill it quickly before it spawns a Putti, it won't spawn a turret-blocking door. Otherwise, destroy the turrets on the door to proceed.

Continue through the next opening to a series of platforms leading to another doorway. This path leads outside to the Opha Superior. While not a boss, it is dangerous as it spawns Guardians and Puttis.

After defeating the Opha Superior, clear remaining Guardians and destroy the three turrets on the door to open it.

Go through the middle ring and enter again. Jump across platforms to the middle ring where a ramp will appear, granting access to the upper ring.

A final Opha guards the doorway to the vault. Prepare for the final boss of the story.

Boss: The Sentinel This is the final boss of borderlands the presequel and is a lengthy encounter with multiple forms. After depleting the shield of each form, The Sentinel teleports to the center and unleashes a shockwave to initiate the next form; avoid this shockwave as it deals significant damage or can kill you outright.

Form 1: The Sentinel attacks with its staff at close range and can twirl it to deflect shots. It also fires electric balls that can be avoided by constant movement.

Form 2: This form is fire-elemental. It retains some previous attacks, but the electric balls are now fire, and it can also float.